Abstract :
A new transformer model based on core topology is
developed. The model simulates the transformer as a set of
coupled inductances. Winding flux linkages are chosen as state
variables and currents are computed from the flux linkages
using the directly-formed inverse inductance matrix, the rmatrix.
Due to the strong magnetic coupling among the
windings, the inductance matrix of a transformer is illconditioned.
Directly forming the r-matrix will not only speed
up the computation but also make it more stable. Transformer
core saturation is represented by its anhysteretic magnetization
curve. Eddy current and hysteresis losses of the core, and stray
losses of the transformer are accounted for by a resistive load on
the secondary. Winding capacitances are lumped to the
terminals, the model is thus accurate up to 5 kHz. A supporting
routine is written to generate k-i curve data for each segment of
the core and the other input data for EM". The model has
been incorporated into the Alternative Transients Program
(ATP), the BPA EMTP, for evaluation, and has passed the
benchmark test of the GPU line energization test of 1973.
